At the University of Valencia, scientists found that the SARS-CoV-2 membrane protein folds and dimerizes while being made, guided by a key hydrophobic cluster.
This early assembly step is essential for forming new virus particles.
www.biorxiv.org/content/10.6...
Overall, we show that (a) once M is targeted to the ER, the EMC and MPT mediate TMD insertion and (b) TMD bundles dimerize co-translationally while assited by chaperones.
Thanks to all co-authors, it was a long ride after many years of work!
@memprotlabuv.bsky.social @ismaelmingarro.bsky.social
(7) Finally, we screened for ER membrane protein chaperones, identifying a cluster of different cofactors that were especifically proximal to multipass truncates, likely accomodating M co-translational folding.
(6) This revealed different interesting patters of proximity to several subunits of ER insertases like EMC or the multipass translocon, and specific proximity to the post-translational glycosylation machinery (OST-B).
(5) Then, we used proximity labeling in human cells with single and multipass truncated versions of M protein, to study the membrane vicinal proteome of the different TMDs as they are inserted in the ER membrane.
(4) We recorded another whole force profile upon cluster disruption, which showed that by altering monomer-monomer TMD interactions, a deficiency in the folding of the downstream cytosolic domain was observed.
(3) MD simulations confirmed this, and revealed a cluster of hydrophobic residues in the dimer interface that, when mutated, proved to be essential for protein dimerization, Spike recruitment, virus entry and viral particle formation.
(2) We reveal that TMD 2 acts as the pivotal scaffold for TMD bundle dimerization, mediating interactions with other TMDs in the opposite monomer. This gave us a hint of a likely co-translational dimerization event.
In this work, we (1) recorded a full-length force profile analysis on M protein describing its cotranslational folding at two different labeling times.
This revealed sequential, fast insertion of the three TMDs; while the cytosolic domain folds at a slower rate.
Excited to finally share the preprint from my main PhD project where we characterized SARS-CoV-2 membrane (M) protein biogenesis.
www.biorxiv.org/content/10.6...
M protein mediates virus assembly, so by describing its biogenesis pathway we reveal vulnerabilities amenable to therapeutic targeting:
Thrilled to share our latest study, led by @reikatei.bsky.social, in @natchembio.nature.com! We began by asking a simple question—how do cells know if they have too much of a lipid in a particular membrane, and how do they respond to rectify this imbalance?
www.nature.com/articles/s41...
More info 👇
New work describes our efforts to achieve CRISPR editing of the mitochondrial genome.
www.biorxiv.org/lookup/conte...
Personal investigador del #I2SysBio (@csic.es-@uv.es) y del Laboratorio de Proteínas de Membrana de la @ccbiologiquesuv.bsky.social han identificado una región clave de la proteína Spike del SARS-CoV-2, esencial para que el virus pueda entrar en las células humanas.
www.i2sysbio.es/communicatio...
🗞️Investigadors del #I2SysBio (
@csic.es-@uv.es) i del Laboratori de Proteínes de Membrana de
@ccbiologiquesuv.bsky.social descobreixen el paper de “l’àncora” del coronavirus: la part menys coneguda de la proteïna espícula (spike) és clau per a la infecció
🔗Més informació:
Is it possible to engineer new cellular life from the bottom up?
The Göpfrich group @kgoepfrich.bsky.social @mpi-mr.bsky.social have designed an RNA origami nanotube 🟡 to mimic the cytoskeleton:
www.nature.com/articles/s41...
It was a fun challenge to animate T7 RNA polymerase 🔵
#blender #b3d
Broad-spectrum synthetic carbohydrate receptors (SCRs) inhibit viral entry across multiple virus families
Targeting sugar molecules shared on the surface of several virus families new compounds were found that can neutralise viruses.
www.science.org/doi/...
1/2
Excited to share our new review on ESCRT-III! If you're intrigued by how cells keep their membranes in shape, this one's for you 🌀✂️
Our story on GroEL/ES action during cotranslational folding is now published @natcomms.nature.com. Led by former-student Alzbeta Roeselova, and in collaboration with Rado Enchev's lab @crick.ac.uk.
www.nature.com/articles/s41...
How is N-glycosylation regulated? Check out our story, part of a terrific collaboration with our colleagues at Stanford and Northwestern. Congratulations to everyone!
rdcu.be/eQNsJ
Structural insights into MERS and SARS coronavirus membrane proteins
www.nature.com/articles/s42...
This was a pretty cool collab between our @memprotlabuv.bsky.social led by @ismaelmingarro.bsky.social at @uv.es and @rongellerlab.bsky.social at @i2sysbio.es
And thanks to all authors for the effort put into this!
However, in order to allow fusion and infection, big rearrangements of the Spike protein are needed, so it makes sense that the opposite face is also essential for viral entry.
That might be why Spike TMD is the only fully-conserved TMD across all SARS-CoV-2 VOCs...
Strutural modeling of the TMD trimer also favored this motif to be responsible for stabilising the trimer, as it orients it to the inner core of the trimer in almost all models.
This motif might favor a transient oligomeric state in specific steps of the membrane fusion process.
Another controversy that existed was if the TMD can oligomerize by itself thus aiding Spike trimerization, since there are no structures of full-length pre-fusion Spike.
We showed that it does, and the only way to disrupt the oligomer is to disrupt the GxxAG motif.
As for viral entry, scrambling the TMD sequence completely disrupted Spike cell-cell fusion activity...
and mutating the AG from the GxxAG motif also did! This residues might be playing an essential role in fusing the viral and host membranes, but how?
To investigate how these structural motifs allow viral entry, we applied different functional approaches:
First, we showed that all mutations that blocked viral entry (except one) were able to reach the cell surface, so the infectivity deficiency was not due to a defect in protein trafficking...
Point mutations on both sides of the TMD helix had an influence on pseudovirus entry, especially through a small GxxAG motif but also other specific hydrophobic residues from the opposite, bulkier side.
It was shocking to see how almost any change that you apply to this region abolishes viral entry of Spike-pseudotyped VSV particles.
Any whole-turn scan and insertion on the N-terminal and core regions of the TMD blocked infectivity, implying essential structural motifs within the helix.
There was controversy in the literature since SARS-CoV-1 about if the Spike protein TMD was relevant for protein funcion and viral infectivity, so we decided to design a broad panel of mutations, insertions and whole-turn scans to adress this problem thoroughly.
